Depression and Heart Disease: How They're Connected

Anyone who has heart disease or is close to someone with heart disease can understand how and why depression can creep in. Heart disease may be the first serious health problem a person faces, or it can be just one more physical challenge added to the insult of diabetes, hypothyroidism, and other debilitating conditions. Regardless, the result is the same.

Your lifestyle, diet, and many other routines that were previously taken for granted may undergo radical changes. You are faced with fear, confusion, uncertainty about the future, and perhaps even brushes with death. These are powerful ingredients that can easily mix into a brew of depression.

Depression is more than just feeling bad

We all feel bad, are in a bad mood, or claim to be “depressed” from time to time. We may also experience some of the classical symptoms of depression such as loss of interest in work and recreational activities, difficulty concentrating, sleep problems, loss of appetite, feelings of helplessness, and even thoughts of suicide. Such emotions are commonly triggered by a major setback, loss of a loved one or even the death of a family pet. It is certainly a matter of degree, but when these feelings persist for more than a couple of weeks, it could represent clinical depression that should be addressed professionally.

Emerging science has begun to reveal that what we experience psychologically as depression is also associated with many powerful physical changes that often occur without any immediately recognizable symptoms. These include hormonal distortions, reduced immunity and inflammation. There is a strong link between depression and heart disease that has proven out in study after study. One such study found that depressed persons suffer a four-fold greater heart attack risk.

Here are just a few of the negative physical responses researchers have observed in connection with depression:

C-Reactive Protein (CRP) is a well-known marker of inflammation associated with an elevated risk for heart disease. CRP levels have been shown to be higher in depressed persons.

Researchers have noted that levels of other inflammatory proteins such as interleukin-1β (IL-1β) and Tumor Necrosis Factor-α (TNF-α) increase as depression deepens.

Strong emotions are known to release stress hormones and depression is no exception. The release of additional amounts of common stress hormones such as cortisol and norepinephrine can cause hypertension, increase insulin resistance and lead to diabetes, all of which increase the risk of heart disease.

Depression can also activate our central nervous system (CNS), which is responsible for regulating many bodily functions including heart rate and heart rate variability (HRV). The CNS is composed of the sympathetic nervous system (SNS), which among other things increases heart rate and the parasympathetic system (PNS) and, in turn, decreases heart rate. When depression increases SNS activity and decreases PNS activity, it also reduces HRV which has been shown to increase vulnerability to cardiac arrhythmias and sudden death.

Elevated homocysteine levels have been frequently associated with an elevated risk of heart disease. Not surprisingly, studies have observed that chronically depressed persons have higher homocysteine levels.

Epidemiologists have noted that the risk of both heart disease and depression is markedly lower among groups that eat large quantities of fish and consequently have high blood levels of omega-3 fatty acids. Omega-3 fatty acids from fish oils have been consistently shown to decrease the risk for heart disease and arrhythmias. Could low omega-3 levels also serve as a novel marker and treatment goal for depression as well as heart disease – a so-called “two for one” magic bullet?